He knelt on the bed and fussed with the covers some, trying for an equitable—if not chivalrously so—division of blankets. He bent forward to kiss at a bite-mark he'd left on her shoulder.

His back went “pop.”

Somewhere down in the lumbar, somewhere just above his tailbone, a deep and unforgiving pop, ominous as the cocking of a revolver. He put his hand there and it felt OK, so he cautiously lay back. Three-quarters of the way down, his entire lower back seized up, needles of fire raced down his legs and through his groin, and he collapsed.

He barked with pain, an inhuman sound he hadn’t known he could make, and the rapid emptying of his lungs deepened the spasm, and he mewled. Linda opened a groggy eye and put her hand on his shoulder. “What is it, hon?”

He tried to straighten out, to find a position in which the horrible, relentless pain returned whence it came. Each motion was agony. Finally, the pain subsided, and he found himself pretzelled, knees up, body twisted to the left, head twisted to the right. He did not dare budge from this posture, terrified that the pain would return.